slide {
    background-position: center;
    background-repeat: no-repeat;
    background-size: contain;
}
$(document).ready(function(){
    // for every article tag inside a slide tag
    $("slide > article").each(function(){
        // copy the article name to the parentNode's (the slide) ID
        this.parentNode.id=$(this).attr('name');
    });
});

Next Slide